From Fairbanks to the beginning of the Dalton Hwy/Haul Road, it is good asphalt/tar with some nice curves.
From beginning of the Dalton (Mile 0) to around Mile 10 (used to be Mile 18.5 but there is construction going on to bring the pavement south a few miles farther) it is gravel, which can be loose, muddy, dusty, or a combination of all three (if it is not snowing) depending on road maintenance and the weather. Broken pavement (as long as there is no oncoming traffic, use the entire road width to dodge potholes and loose gravel in the broken areas) for about 5 miles, then gravel again to about Mile 37. Nice pavement, fairly new, to Mile 49.5 then back to gravel all the way to Mile 90, where you hit some old, often potholed, pavement. That continues past the Arctic Circle (Mile 115), on past Coldfoot (Mile 175) for about another 20 miles, with new construction adding more miles of pavement at the north end, too.
Just before the Arctic Circle, from Mile 110 to 112, there is a gravel hill known as Beaver Slide. It is usually pretty good. At the bottom, however, you begin a stretch of broken pavement again for a mile or two. There are also some pretty bad breaks north of the Arctic Circle for almost 20 miles, until you climb up to Gobblers Knob, and then again descending to the Prospect Creek area. Once past Pump Station 5, along the Jim River, it is pretty good again.
Just don't get in a big hurry. Never outride your sight distance, as conditions can change very, very quickly. And keep an eye on your mirrors as traffic can creep up behind you when you aren't expecting it.
If road maintenance is going on in one of the gravel areas, i.e. watering the road surface to soften it, then grading to rearrange the bumps, it can be a bit of a challenge with the mud and the berms pushed up by the graders. Again, just take your time and it is all manageable.
A rider who came up last year on a Concours/ZG1000 sport tourer just posted some great videos on You Tube of his ride to Deadhorse. Take a look at those and you will get a really good idea of what you can expect. Sport Touring the Dalton
I believe the Dalton Hwy starts with #3, but they're all good and worth watching.